The Interleukin-6/Signal Transducer and Activator of Transcription 3/Snail Pathway Mediates Epithelial-Mesenchymal Transition in Recurrent Liver Cancer after Radiofrequency Ablation

Background: Radiofrequency ablation (RFA), as a relatively mature and minimally invasive therapy for hepatocellular carcinoma (HCC), has become an important treatment strategy. However, tumor recurrence remains common and epithelial-mesenchymal transition (EMT) is thought to play an important role in this process. Based on limited sample volumes harvested from patients, we established a heat-treated cell line and mouse model, in addition to collecting patient samples, to investigate the mechanism of recurrence after RFA due to incomplete ablation. Methods: We heat-treated H22 cells using a water bath to determine a suitable temperature for incomplete RFA. Male BALB/c mice were orthotopically transplanted with H22 cells and then subjected to incomplete ablation. Clinical specimens collected from patients with HCC who had undergone RFA were also collected. Changes in EMT biomarkers were detected by real-time polymerase chain reaction, western blotting, and immunofluorescence. Findings: Incomplete RFA promoted EMT, downregulated E-cadherin, upregulated vimentin and Snail, and enhanced the phosphorylation of signal transducer and activator of transcription 3 (STAT3) both in vivo and in vitro. Moreover, interleukin (IL)-6 secretion increased after heat treatment in H22 cells. AG490, an IL-6 inhibitor, was found to block the occurrence of the EMT. Interpretation: Insufficient ablation performed at low temperatures can successfully induce EMT, which is mediated by the IL-6/STAT3/Snail pathway in cell and mouse models. Funding: Supported by National Natural Science Foundation of China (61671276) and the Natural Science Foundation of Shandong Province (2014ZRE27479, ZR2018PH032, ZR201709250376). Declaration of Interest: All authors declare no conflicts-of-interest related to this article. Ethical Approval: The study design was approved by the appropriate ethics review board.